Diffusion coefficients of low-energy protons upstream of quasi-parallel interplanetary shocks

Conference · Sun Jan 01 04:00:00 EST 1984 · Adv. Space Res.; (United States)

OSTI ID:5823080

Van Nes, P; Reinhard, R

Results are presented of a study of the diffusion coefficient for low-energy protons upstream of three interplanetary shocks observed on ISEE-3. The intensity increase as the shock approaches can be fitted by a running exponential, the e-folding time t-asterisk of which is assumed to be a direct measure of the diffusion coefficient. The energy dependence of t-asterisk close to the shock (0-60 Re) is derived from the four energy channels covering the range 35-238 keV. The t-asterisk in the low energy channels (less than 100 keV) increases with distance away from the shock. However t-asterisk decreases above 100 keV and roughly beyond 100 Re, so that the diffusion coefficient becomes independent of energy. It is suggested that the energy-independence of t-asterisk in a region well upstream of the shock is the result of enhanced parallel scattering through 90-deg pitch-angles for higher energy (larger gyroradius) particles which are more sensitive to variations in the transverse direction of the magnetic field. 7 references.

• Research Organization: ESA, Noordwijk, Netherlands
• OSTI ID: 5823080
• Report Number(s): CONF-8406167-
• Conference Information: Journal Name: Adv. Space Res.; (United States) Journal Volume: 4
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
DIFFUSION
ELEMENTARY PARTICLES
FERMIONS
HADRONS
INTERPLANETARY SPACE
NUCLEONS
PROTONS
SCATTERING
SHOCK WAVES
SPACE